Discharge lamp with partition



Dec. 29, 1942. E. LEMMERS 2,306,628

DISCHARGE LAMP WITH PARTITION Filed Nov. 2, 1940 lnventov:

Eu ene Lemmer-s, bWMM His Attorney.

Patented Dec. 29, 1942 UNITED STATES 2.30am mscmmcn mm wrm raarmou Eugene Lemm'era, Cleveland Heights, Ohio, assignortoGeneralElectricOompany,aoorporation of New York Application November 2, 1940, Serial No. 364,356

. l 3 Claims.

- My invention relates to electric discharge tubes of the type having plural adjacent compartments or channels through which arc streams of different potentials may fiow without current leakage from one to the other. More particularly it relates to an improved means for separating those channels one from the other without current leakage.

Hitherto, in the construction of tubes of the aforesaid type, it has been the general practice to use as separators between the plural channels, walls of glass which were integral with the main glass wall or envelope of the tube. Attempts have been made to employ mica shields in place of these glass walls but such attempts have generally been unsuccessful for the reason that it is difficult to obtain a sufilciently close contact or fit between the edge of the mica and the glass to prevent crevices or gaps through which current leakage can take place. The difllculty is particularly troublesome and practically insurmountable where production methods require relatively large manufacturing tolerances. Now I have found these difficulties can be overcome by a relatively simple and economical construction of the mica separator. Generally speaking, the improved construction comprises an added member associated with the mica edge whereby the length of the portion of the leakage path immediately adjacent the tube wall is considerably increased. In other words, the effective width of the partition edge and the width of tube wall covered by the partition edge are made to exceed the gap between partition edge and wall- It is therefore an object of my invention to provide an electron stream separator of simplifled and economical construction.

A further object of my invention is to provide a separator for tubes of the aforementioned type whereby the manufacture of said tubes may be considerably simplified and the cost thereof reduced.

of species thereof.

For a more complete understanding of the means whereby I attain these objects reference may be had to the following detailed description terial and closed at their lower ends. Such idention will appear from the following description and accompanying drawing in which like figures tween electrodes 3.

tical cup cathodes activated only internally are of course primarily intended for operation on alternating current, as is well understood in the art. The saidelectrodes are each positioned in one of the parallel channels or compartments formed in the envelope by the longitudinal partition or separator 4. These channels will serve as guideways for a U-shaped are between the electrodes. The separator 4 is preferably, but not necessarily, of an insulating material such as mica, while envelope 2 may be formed in the usual manner of glass or quartz. Suitable conventional base connections are provided by threaded shell 5 and end contact 6 connected by leads 1 to the respective electrodes. An end shield 8 which takes the form of a disc of mica or other material may be provided to close off the lower portion of the tube if desired. Likewise a starting electrode 9 attached to one electrode 3 and projecting through and below disc 8 to the vicinity of the other electrode 3 may be provided. Except for the opening Ill caused by the fact that the separator 4 stops short of the upper end of the tube, the separator or partition 4 thus forms a complete barrier to the passage of current be- However, with the internally activated cup electrodes 3-3 located as shown in Pig. 2 lengthwise of their channels in the envelope 2, the effective length of the discharge path between the electrode mouths via the' intercommunication of the channels at the upper end of the partition 4 and envelope 2 toward which the electrode mouthsare presented is less than that of the path around the lower end of the partition 4 that would exist in the absence of the shield 8, and the voltage required to produce a discharge via the aforesaid intercommunication is less than that required to produce discharge via the path around the lower partition end.- In alternating current operation, furthermore, ionization to maintain short-circuiting discharge along the 'latter path dies out during each A. C. half cycle, since there is no ionizing emission from the outsides of the cup electrodes 3-3. The relatively low electron emission from the cold cathodes 3-3 is also unfavorable to such and'the glass, due to the imperfect fit resulting from irregularities in the tube wall and in the mica edges. Under ordinary conditions of manu- I iacture it is practically impossible to avoid clearances or gaps of at least 0.010 inch between mica and glass at some points. Crevices of even this size will generally permit suiilcient leakage between the arcs to seriously interfere with the operation of the tube.

Now I have found that if a second mica partition be placed parallel to the first and separated therefrom by many times the distance of the clearance between the mica and wall the leakage is stopped. Thus, as indicated by Fig. 2, the partition or separator 4 may comprise two separate mica sheets II and I2 spaced apart by separators ii. In this way. the effective width of the partition edge and the width of tube wall covered thereby are made considerably greater than the gap between them. Where the voltage between the arc streams in the adjacent channels is of the order of 30 volts, I have found that the separation distance of the sheets should be at least four times as great as the greatest clearance betweenthe glass wall and the mica. For greater voltage diiferences it will be necessary to increase this ratio if the leakage is to be stopped.

In the Fig. 3 I have shown a still simpler construction of the separator. Here the separator consists of a single mica sheet 4 having flaps or flanges l4|4 folded to extend along the tube walls for the required distance. In this case, it will be necessary that the projection of the flap along the tube wall be many times the clearance between the main mica edge and the wall, i. e., that the distance a: be at least fourtimes the distance 1! (where the arc potentials differ by about volts). It will be understood that the dimension 1: is shown somewhat exaggerated for the sake of clarity.

In Fig. 4 is shown an alternative construction for separating adjacent arc chambers or compartments in opposite ends of a cylindrical tube by means of a separator or partition 4 transverse to the axis of the tube. Arcs formed between activated electrodes l5 and I6, and I1 and I! are series connected across terminals 2l--2l, the separator 4, which may be of metal, serving as part of the series circuit. If the separator 4 is of insulating material, suitable metallic leads through'it will be necessary to complete the electrical circuit. The separator 4 is constructed as in Fig. 2. The electrodes IE to l8 may be initially brought up to operating temperature by insulated heaters 20 each positioned within one of the electrodes l5 to I! and all forming with shield 4 a series circuit across terminals lL-IO. Mercury drop 22 may serve as a source of ionizable working vapor.

Although I am unable to state with certainty a theory for the improved operation resulting from my invention, it is my belief that the added flaps and mica sheets so increase the length of that portion of the leakage path which is immediately adjacent to the tube wall that insufllcient ions may leak through to sustain an arc,

modifications within the scope'of the appended claims may occur to those skilled in the art to which it pertains.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric discharge device comprising a tubular discharge envelope with a cup electrode in one side thereof presenting its mouth toward one end of the envelope and activated internally only, a coacting cup electrode in the other side of said envelope presenting its mouth toward the same end thereof, a longitudinal partition between said cupelectrodes effectively shorter than the envelope and dividing its interior into longitudinal channels communicating at the partition end toward which the electrode mouths are presented, the longitudinal partition edges fitting the tube wall imperfectly but covering widths of wall surface so far exceeding the gaps between edges and wall as to prevent leakage of discharge current through the gaps, and the cup electrodes being so located lengthwise of their respective channels that the eifective length or resistance of the path for discharge between the electrode mouths via the intercommunication aforesaid is less than that of a path around the other end of said partition.

2. An electric discharge device comprising a tubular discharge envelope with coacting cup cathodes therein activated internally only and presenting their mouths toward the same end of the envelope, a longitudinal partition between said cup electrodes eifectively shorter than the envelope and dividing its interior into longitudinal channels communicating at the partition end toward which the electrode mouths are presented, the longitudinal partition edges fitting the tube wall imperfectly but covering widths of wall surface so far exceeding the gaps between edges and wall as to prevent leakage of discharge current through the gaps, and the cup electrodes being so located lengthwise of their respective channels that the voltage required to produce discharge between the electrode mouths via the intercommunication aforesaid is less than that required to produce discharge between the mouth of one electrode and the exterior of the other around the other end of said partition.

3. An electric discharge device comprising a tubular discharge envelope with a cold operating cup electrode in one side thereof presenting its i. e., by pushing the leakage arc up to the tube wall. the ion loss to that wall becomes great enough to quench the arc until a greater voltage is supplied. The phenomenon is analogous to the progressive increase in the necessary arc sustaining voltage which occurs when the envelope about any are is constricted progressively.

It will be understood of course that my invention is not limited in any way by any theory of operation recited here. Further it will be understood my invention is not to be limited by any structural details herein shown and that many mouth toward one end of the envelope and acti vated internally only, a coacting cold operating cup electrode in the other side of said envelope presenting its mouth toward the same end thereof, a longitudinal partition between said cup electrodes eifectively shorter than the envelope and dividing its interior into longitudinal channels communicating at the partition end toward which the electrode months are presented, the longitudinal partition edges fitting the tube wall imperfectly but covering widths of wall surface so far exceeding the gaps between edges and wall as to prevent leakage of discharge current through the gaps, and the cup electrodes being so located lengthwise of their respective channels that the voltage required to produce discharge between the electrode mouths via the intercommunication aforesaid is less than that required to produce discharge between the mouth of one.

electrode .and the exterior of the other around the other end of said partition.

EUGENE LEIUIERS. 

